U.S. patent application number 15/459605 was filed with the patent office on 2017-06-29 for organic light-emitting diode (oled) display panel and display apparatus.
The applicant listed for this patent is Shanghai Tianma AM-OLED Co., Ltd., Tianma Micro-Electronics Co., Ltd.. Invention is credited to Yuji HAMADA, Wei HE, Zhihong LEI, Chen LIU, Yinhe LIU, Jinghua NIU, Xiangcheng WANG.
Application Number | 20170187003 15/459605 |
Document ID | / |
Family ID | 58822423 |
Filed Date | 2017-06-29 |
United States Patent
Application |
20170187003 |
Kind Code |
A1 |
LEI; Zhihong ; et
al. |
June 29, 2017 |
ORGANIC LIGHT-EMITTING DIODE (OLED) DISPLAY PANEL AND DISPLAY
APPARATUS
Abstract
An organic light-emitting diode (OLED) display panel and an OLED
display apparatus are provided. The OLED display panel comprises: a
first electrode and a second electrode disposed in a stacked
configuration, wherein at least one of the first electrode and the
second electrode is a light-output-side electrode; an organic
luminescent layer disposed between the first electrode and the
second electrode; an electron transport layer disposed between the
organic luminescent layer and the second electrode; and an optical
coupling layer disposed on a surface of the light-output-side
electrode far away from the organic luminescent layer. The electron
transport layer contains element ytterbium (Yb) with a volume
percentage equal to or less than approximately 3%.
Inventors: |
LEI; Zhihong; (Shanghai,
CN) ; NIU; Jinghua; (Shanghai, CN) ; HAMADA;
Yuji; (Shanghai, CN) ; LIU; Chen; (Shanghai,
CN) ; WANG; Xiangcheng; (Shanghai, CN) ; HE;
Wei; (Shanghai, CN) ; LIU; Yinhe; (Shanghai,
CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Shanghai Tianma AM-OLED Co., Ltd.
Tianma Micro-Electronics Co., Ltd. |
Shanghai
Shenzhen |
|
CN
CN |
|
|
Family ID: |
58822423 |
Appl. No.: |
15/459605 |
Filed: |
March 15, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 27/322 20130101;
G02B 1/04 20130101; H01L 51/0059 20130101; H01L 51/006 20130101;
H01L 51/5072 20130101; H01L 51/5218 20130101; H01L 51/0074
20130101; H01L 51/5012 20130101; H01L 2251/558 20130101; H01L
51/5056 20130101; H01L 2251/301 20130101; H01L 51/504 20130101;
H01L 51/0073 20130101; H01L 51/0052 20130101; H01L 51/5076
20130101; H01L 51/5016 20130101; H01L 2251/308 20130101; H01L
51/5231 20130101; H01L 51/0072 20130101; H01L 51/0071 20130101;
H01L 51/005 20130101; H01L 51/0061 20130101; H01L 51/007 20130101;
H01L 51/5275 20130101; H01L 51/5234 20130101 |
International
Class: |
H01L 51/52 20060101
H01L051/52; H01L 51/50 20060101 H01L051/50; H01L 27/32 20060101
H01L027/32 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 14, 2016 |
CN |
201611152979.X |
Claims
1. An organic light-emitting diode (OLED) display panel,
comprising: a first electrode and a second electrode disposed in a
stacked configuration, wherein at least one of the first electrode
and the second electrode is a light-output-side electrode; an
organic luminescent layer disposed between the first electrode and
the second electrode; an electron transport layer disposed between
the organic luminescent layer and the second electrode; and an
optical coupling layer disposed on a surface of the
light-output-side electrode far away from the organic luminescent
layer, wherein the electron transport layer contains element
ytterbium (Yb) with a volume percentage equal to or less than
approximately 3%.
2. The OLED display panel according to claim 1, wherein the optical
coupling layer includes materials having the following chemical
formulas: ##STR00004## wherein Ar.sub.2, Ar.sub.3 and Ar.sub.4 are
aryl groups, R.sub.1 to R.sub.28 are alkyl groups or aryl groups,
and A is an organic group.
3. The OLED display panel according to claim 1, wherein a thickness
of the optical coupling layer approximately ranges from 500 .ANG.
to 800 .ANG..
4. The OLED display panel according to claim 1, wherein a light
transmittance of the light-output-side electrode is approximately
30% to 50%.
5. The OLED display panel according to claim 4, wherein a total
light transmittance of the optical coupling layer combined with the
light-output-side electrode is equal to or larger than
approximately 65%.
6. The OLED display panel according to claim 1, wherein: the second
electrode is the light-output-side electrode and includes materials
of silver or a silver-based alloy; and the first electrode
comprises a first transparent conductive film, a second transparent
conductive film, and a reflective film sandwiched between the first
transparent conductive film and the second transparent conductive
film.
7. The OLED display panel according to claim 6, wherein: the first
transparent conductive film and the second transparent conductive
film comprise indium tin oxide or indium zinc oxide; and the
reflective film comprising silver or a silver-based alloy has a
thickness of approximately 50 nm to 150 nm.
8. The OLED display panel according to claim 6, wherein: the second
electrode comprises a silver-based alloy; the volume percentage of
silver in the alloy is equal to or larger than approximately 80%;
and a thickness of the second electrode is approximately 10 nm to
20 nm.
9. The OLED display panel according to claim 1, wherein: the first
electrode is the light-output-side electrode, and comprises
transparent conductive materials; and the second electrode
comprises silver or a silver-based alloy.
10. The OLED display panel according to claim 9 wherein: the
transparent conductive materials include indium tin oxide or indium
zinc oxide.
11. The OLED display panel according to claim 9, wherein: the
second electrode comprises a silver-based alloy, wherein the volume
percentage of silver is equal to or larger than approximately 80%;
and a thickness of the second electrode is approximately 50 nm to
150 nm.
12. The OLED display panel according to claim 1, wherein: the
organic luminescent layer comprises red, green and blue
light-emitting materials.
13. The OLED display panel according to claim 12, wherein: white
light is obtained by mixing lights emitted from the red, green, and
blue light-emitting materials.
14. The OLED display panel according to claim 13, further
including: a color filter layer disposed at the light output side,
such that the white light emitted by the OLED display panel becomes
colored light after passing through the color filter layer.
15. The OLED display panel according to claim 12, wherein: the red
and the green light-emitting materials include phosphorescent
materials, and the blue light-emitting materials include
fluorescent materials.
16. The OLED display panel according to claim 15, wherein: the red,
the green, and the blue light-emitting materials include host
materials doped with guest materials; and the red light-emitting
materials comprise one host material or two host materials, the
green light-emitting materials comprise at least two host
materials, and the blue light-emitting materials comprise one host
material or two host materials.
17. The OLED display panel according to claim 15, wherein the
fluorescent materials include thermally activated delayed
fluorescent materials.
18. The OLED display panel according to claim 1, further including:
a hole transport layer disposed between the first electrode and the
organic luminescent layer.
19. An organic light-emitting diode (OLED) display apparatus
comprising an OLED display panel, wherein the OLED display panel
comprises: a first electrode and a second electrode disposed in a
stacked configuration, wherein at least one of the first electrode
and the second electrode is a light-output-side electrode; an
organic luminescent layer disposed between the first electrode and
the second electrode; an electron transport layer disposed between
the organic luminescent layer and the second electrode; and an
optical coupling layer disposed on a surface of the
light-output-side electrode far away from the organic luminescent
layer, wherein the electron transport layer contains element
ytterbium (Yb) with a volume percentage equal to or less than
approximately 3%.
20. The OLED display apparatus according to claim 19, wherein: the
optical coupling layer includes materials having the following
chemical formulas: ##STR00005## wherein Ar.sub.2, Ar.sub.3 and
Ar.sub.4 are aryl groups, R.sub.1 to R.sub.28 are alkyl groups or
aryl groups, and A is an organic group.
21. The OLED display apparatus according to claim 19, wherein a
thickness of the optical coupling layer approximately ranges from
500 .ANG. to 800 .ANG..
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application claims priority of Chinese Patent
Application No. 201611152979.X, filed on Dec. 14, 2016, the entire
contents of which are hereby incorporated by reference.
FIELD OF THE INVENTION
[0002] The present disclosure generally relates to the field of
organic light-emitting diode (OLED) display technology and, more
specifically, relates to an OLED display panel and an OLED display
apparatus thereof.
BACKGROUND
[0003] OLEDs have become one of the most important trends in the
display industry, because of their various technological
advantages, such as working without a backlight source, high
contrast ratio, thin thickness, wide viewing angle and fast
response. An existing OLED panel comprises a cathode, an electron
transport layer, a light-emitting layer, a hole transport layer, an
anode, and a substrate. In operation, a bias voltage is applied
between the cathode and the anode. As a result, holes and electrons
pass through the energetical barrier, and respectively migrate from
the hole transport layer and the electron transport layer towards
the light-emitting layer where electrons and holes further
recombine to form excitons.
[0004] The formed excitons are substantially unstable, which
release and transfer the energy to organic luminescent molecules in
the light-emitting layer. The transferred energy leads to the
energetical transition in the organic luminescent molecules from
the ground state to the excited state. The light emission is
consequently generated from the luminescent molecules by the
spontaneous radiation decay from the excited state back to the
ground state.
[0005] In an OLED display panel, the energetical barrier at the
interface between the organic material and the electrode often
determines the number of injected carriers, panel brightness and
efficiency. However, the interface barrier between the electron
transport layer and the cathode may be substantially high in the
existing OLED display panels, resulting in the limited capability
of electron injection and, accordingly, the poor performance of
OLED display panel.
[0006] The disclosed OLED display panel and OLED display apparatus
thereof are directed to solve one or more problems set forth above
and other problems.
BRIEF SUMMARY OF THE DISCLOSURE
[0007] One aspect of the present disclosure provides an OLED
display panel. The OLED display panel comprises: a first electrode
and a second electrode disposed in a stacked configuration, wherein
at least one of the first electrode and the second electrode is a
light-output-side electrode; an organic luminescent layer disposed
between the first electrode and the second electrode; an electron
transport layer disposed between the organic luminescent layer and
the second electrode; and an optical coupling layer disposed on a
surface of the light-output-side electrode far away from the
organic luminescent layer. The electron transport layer contains
element ytterbium (Yb) with a volume percentage equal to or less
than approximately 3%.
[0008] Another aspect of the present disclosure provides an OLED
display apparatus. The OLED display apparatus comprises an OLED
display panel. The OLED display panel comprises: a first electrode
and a second electrode disposed in a stacked configuration, wherein
at least one of the first electrode and the second electrode is a
light-output-side electrode; an organic luminescent layer disposed
between the first electrode and the second electrode; an electron
transport layer disposed between the organic luminescent layer and
the second electrode; and an optical coupling layer disposed on a
surface of the light-output-side electrode far away from the
organic luminescent layer. The electron transport layer contains
element ytterbium (Yb) with a volume percentage equal to or less
than approximately 3%.
[0009] Other aspects of the present disclosure can be understood by
those skilled in the art in light of the description, the claims,
and the drawings of the present disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The following drawings are merely examples for illustrative
purposes according to various disclosed embodiments and are not
intended to limit the scope of the present disclosure.
[0011] FIG. 1 illustrates a schematic diagram of an exemplary OLED
display panel consistent with disclosed embodiments;
[0012] FIG. 2a illustrates a performance comparison between an
existing OLED device and an exemplary OLED device consistent with
disclosed embodiments. FIGS. 2b-d illustrate a performance
comparison between an existing display panel and an exemplary OLED
display panel consistent with disclosed embodiments;
[0013] FIGS. 3a-c illustrate a performance comparison of five
exemplary OLED display panels consistent with disclosed
embodiments;
[0014] FIG. 4a illustrates thickness-dependent refractive index of
an exemplary optical coupling layer in an exemplary OLED display
panel consistent with disclosed embodiments;
[0015] FIG. 4b illustrates thickness-dependent extinction
coefficient of an exemplary optical coupling layer in an exemplary
OLED display panel consistent with disclosed embodiments;
[0016] FIG. 5 illustrates a relationship between light
transmittance of an exemplary OLED display panel and thickness of
an exemplary optical coupling layer consistent with disclosed
embodiments;
[0017] FIGS. 6a-b illustrate a performance comparison of four
exemplary OLED display panels consistent with disclosed
embodiments;
[0018] FIG. 7 illustrates a schematic diagram of another exemplary
OLED display panel consistent with disclosed embodiments;
[0019] FIG. 8 illustrates a schematic diagram of another exemplary
OLED display panel consistent with disclosed embodiments;
[0020] FIG. 9 illustrates a schematic diagram of another exemplary
OLED display panel consistent with disclosed embodiments;
[0021] FIG. 10 illustrates a schematic diagram of another exemplary
OLED display panel consistent with disclosed embodiments; and
[0022] FIG. 11 illustrates a schematic diagram of an exemplary OLED
display apparatus consistent with disclosed embodiments.
DETAILED DESCRIPTION
[0023] Reference will now be made in detail to exemplary
embodiments of the invention, which are illustrated in the
accompanying drawings. Hereinafter, embodiments consistent with the
disclosure will be described with reference to drawings. Wherever
possible, the same reference numbers will be used throughout the
drawings to refer to the same or like parts. It is apparent that
the described embodiments are some but not all of the embodiments
of the present invention. Based on the disclosed embodiments,
persons of ordinary skill in the art may derive other embodiments
consistent with the present disclosure, all of which are within the
scope of the present invention. Further, in the present disclosure,
the disclosed embodiments and the features of the disclosed
embodiments may be combined under conditions without conflicts.
[0024] FIG. 1 illustrates a schematic structure diagram of an
exemplary OLED display panel consistent with disclosed embodiments.
As shown in FIG. 1, the OLED display panel may comprise a plurality
of thin films disposed in a stacked configuration: a first
electrode 11, a second electrode 12, an organic luminescent layer
13, an electron transport layer 14, and an optical coupling layer
20. Other appropriate components may also be included.
[0025] In particular, at least one of the first electrode 11 and
the second electrode 12 may be disposed at a light output side of
the OLED display panel, i.e., a side where the light is outputted
from the display panel. The electrode disposed at a light output
side is called as a light-output-side electrode. The organic
luminescent layer 13 may be disposed between the first electrode 11
and the second electrode 12. The electron transport layer 14 may be
disposed between the organic luminescent layer 13 and the second
electrode 12. The electron transport layer 14 may contain an
element of ytterbium (Yb) with a volume percentage equal to or less
than 3%. The optical coupling layer 20 may be disposed on the
surface of the light-output-side electrode far away from the
organic luminescent layer 13.
[0026] In one embodiment, as shown in FIG. 1, the second electrode
12 may be disposed at the light output side, i.e., the second
electrode 12 may be a light-output-side electrode, and the first
electrode 11 and the second electrode 12 may be an anode and a
cathode, respectively, which is for illustrative purposes and is
not intended to limit the scope of the present disclosure.
[0027] According to the Fowler-Nordheim tunneling model, the
element Yb in the electron transport layer 14 may reduce the
interfacial energy barrier between the second electrode 12 and the
electron transport layer 14. In existing OLED display panels, the
electron transport layer 14 may not contain the element Yb.
[0028] FIG. 2a illustrates a performance comparison between an
existing OLED device B and an exemplary OLED device A consistent
with disclosed embodiments. The OLED device A contains element Yb
in the electron transport layer 14, while the OLED device B does
not contain the element Yb in the electron transport layer 14.
[0029] As shown in FIG. 2a, the abscissa represents the current
density, J, in the device in a unit of milliamps per square
centimeter (mA/cm.sup.2), and the ordinate represents the bias
voltage U, applied to the device in a unit of volts (V). Given the
same current density J, the bias voltage applied to the OLED device
A may be much lower than the bias voltage applied to the OLED
device B, indicating that the element Yb introduced into the
electron transport layer 14 may reduce the interfacial energy
barrier and thus enhance the electron injection capability.
[0030] FIGS. 2b-d illustrate a performance comparison between an
existing OLED display panel and an exemplary OLED display panel
consistent with disclosed embodiments. As shown in FIGS. 2b-d, C
represents an existing OLED display panel without the element Yb in
the electron transport layer 14, and D represents a disclosed OLED
display panel with the element Yb in the electron transport layer
14.
[0031] As shown in FIG. 2b, the abscissa represents the current
density, J, of the OLED display panel in milliamps per square
centimeter (mA/cm.sup.2), and the ordinate represents the bias
voltage, U, applied to the OLED display panel in volts (V). Given
the same current density J, the bias voltage U applied to the
disclosed OLED display panel D may be much lower than the bias
voltage applied to the existing OLED display panel C, indicating
that the element Yb introduced into the electron transport layer 14
may reduce the interfacial energy barrier between the second
electrode 12 (i.e., the cathode) and the electron transport layer
14, facilitate the electron injection from the second electrode 12,
promote the carrier balance in the OLED display panel and,
accordingly, reduce the operating voltage (i.e., the bias voltage)
of the OLED display panel.
[0032] As shown in FIG. 2c, the abscissa represents the current
density, J, of the OLED display panel in milliamps per square
centimeter (mA/cm.sup.2), and the ordinate represents the luminous
efficiency, E, of the OLED display panel in candela per ampere
(cd/A). Referring to FIG. 2c, given the same current density J, the
luminous efficiency E of the disclosed OLED display panel D may be
much higher than the luminous efficiency E of the existing OLED
display panel C, indicating that the element Yb introduced into the
electron transport layer 14 may increase the luminous efficiency of
the OLED display panel and, accordingly, improve the performance of
the OLED display panel.
[0033] As shown in FIG. 2d, the abscissa represents the operation
time of the OLED display panel in a unit of hour (h), and the
ordinate represents the ratio of the OLED display panel's luminance
(L) to the OLED display panel's initial luminance (L.sub.0).
Referring to FIG. 2d, the luminance of OLED display panels often
decays as the operation time increases. For the disclosed OLED
display panel D, after approximately 370 operation hours, the
luminance may decay to 75% of the initial luminance. For the
existing OLED display panel C, after approximately 160 operation
hours, the luminance may decay to 75% of the initial luminance.
[0034] That is, the operation time of the disclosed OLED display
panel D may be much longer than the operation time of the existing
OLED display panel C, indicating that the disclosed OLED display
panel D may have a longer lifetime than the existing OLED panel C.
In other words, the element Yb introduced into the electron
transport layer 14 may prolong the lifetime of the OLED display
panel.
[0035] FIGS. 3a-c illustrate a performance comparison of five
exemplary OLED display panels consistent with disclosed
embodiments, in which each OLED display panel may be provided with
a different volume percentage of element Yb in the electron
transport layer 14. As shown in FIGS. 3a-c, F denotes an OLED
display panel provided with a 1% volume of element Yb in the
electron transport layer 14, G denotes an OLED display panel
provided with a 3% volume of element Yb in the electron transport
layer 14, H denotes an OLED display panel provided with a 5% volume
of element Yb in the electron transport layer 14, J denotes an OLED
display panel provided with a 7% volume of element Yb in the
electron transport layer 14, and K denotes an OLED display panel
provided with a 9% volume of element Yb in the electron transport
layer 14.
[0036] As shown in FIG. 3a, the abscissa represents the current
density, J, of OLED panel in milliamps per square centimeter
(mA/cm.sup.2), and the ordinate represents the bias voltage, U,
applied to the OLED display panel in volts (V). Referring to FIG.
3a, given the same current density J, the OLED display panels are
arranged in the ascending order of the applied bias voltages U as
follows: G<F<H<J<K.
[0037] As shown in FIG. 3b, the abscissa represents the current
density, J, of OLED display panel in milliamps per square
centimeter (mA/cm.sup.2), and the ordinate represents the luminous
efficiency, E, of OLED display panel in candela per ampere (cd/A).
Referring to FIG. 3b, given the same current density J, the OLED
display panels are arranged in the ascending order of the luminous
efficiency E as follows: K<J<H<F<G.
[0038] As shown in FIG. 3c, the abscissa represents the operation
time of OLED display panel in a unit of hour (h), and the ordinate
represents the ratio of the OLED display panel's luminance (L) to
the OLED display panel's initial luminance (L.sub.0). Referring to
FIG. 3c, given the same ratio of L to L.sub.0, the OLED display
panels G, F and H may have significantly longer operation time than
the other OLED display panels, J and K.
[0039] In summary, the OLED display panels provided with different
volume percentages of element Yb in the electron transport layer 14
may differ in the performance. In practical applications, the
concentration of the element Yb may be adjusted based on the
various performance requirements of the OLED display panel. In one
embodiment, the volume percentage of the element Yb may be
configured to be equal to or less than 3% (i.e., .ltoreq.3%).
According to FIGS. 3a-c, when the volume percentage of the element
Yb is configured to be .ltoreq.3%, the Schottky barrier may be
effectively reduced, and the electron injection capability may be
improved. Thus, the carrier balance in the OLED display panel may
be improved, and the performance of the OLED display panels may be
enhanced, accordingly.
[0040] Returning to FIG. 1, in an operation of the OLED display
panel, the light generated in the organic luminescent layer 13 may
be transmitted through the light-output-side electrode (e.g., the
second electrode 12). When the optical coupling layer 20 is not
disposed on the light output side of the OLED display panel, the
light generated in the organic luminescent layer 13, when being
incident from the optically denser medium (i.e., the second
electrode 12) into the optically thinner medium (i.e., air), may be
reflected at the interface between the light-output-side electrode
and air. Thus, the light transmittance may be decreased, i.e., the
brightness of the OLED display panel may be reduced.
[0041] In the disclosed embodiments, through disposing the optical
coupling layer 20 on the light output side of the OLED display
panel (i.e., disposing the optical coupling layer 20 on the surface
of the light-output-side electrode far away from the organic
luminescent layer 13), the refractive index at the interface
between the light-output-side electrode and air may be modified,
the light reflection may be suppressed and, thus, the light
transmittance may be improved. In other words, the brightness of
the OLED display panel may be improved.
[0042] Disposing the optical coupling layer 20 on the surface of
the light-output-side electrode far away from the organic
luminescent layer 13 may improve the light transmittance by at
least 10%. In addition, sheet resistance of the light-output-side
electrode on which the optical coupling layer 20 is deposited may
be reduced by at least 0.2 .OMEGA./square.
[0043] The optical coupling layer 20 may include various materials
according to various application scenarios. The chemical formulas
of the materials comprising the optical coupling layer 20 may be
given as follows:
##STR00001##
wherein Ar.sub.2, Ar.sub.3 and Ar.sub.4 may be aryl groups, R.sub.1
to R.sub.28 may be alkyl groups or aryl groups, and A may be an
organic group. For example, the optical coupling layer 20 may
include materials with molecular formulas as follows:
##STR00002## ##STR00003##
[0044] Furthermore, the thickness of the optical coupling layer 20
may vary according to various application scenarios. In practical
applications, the thickness of the optical coupling layer 20 may be
adjusted depending on the performance requirements of the OLED
display panel.
[0045] FIG. 4a illustrates thickness-dependent refractive index of
an exemplary optical coupling layer in an exemplary OLED display
panel consistent with disclosed embodiments. As shown in FIG. 4a,
the abscissa represents the thickness of the optical coupling layer
20 in a unit of nanometer (nm), and the ordinate represents the
refractive index of the optical coupling layer 20. Referring to
FIG. 4a, when the thickness of the optical coupling layer 20 ranges
from 500 .ANG. to 800 .ANG., the refractive index of the optical
coupling layer 20 may tend to be stable.
[0046] FIG. 4b illustrates thickness-dependent extinction
coefficient of an exemplary optical coupling layer in an exemplary
OLED display panel consistent with disclosed embodiments. As shown
in FIG. 4b, the abscissa represents the thickness of the optical
coupling layer 20 in a unit of nanometer (nm), and the ordinate
represents the extinction coefficient of the optical coupling layer
20. The extinction coefficient may reflect the light absorption in
the optical coupling layer 20. The light absorption in the optical
coupling layer 20 may be increased as the extinction coefficient
increases. Referring to FIG. 4b, when the thickness of the optical
coupling layer 20 ranges from 500 .ANG. to 800 .ANG., the
extinction coefficient of the optical coupling layer 20 may tend to
be stable.
[0047] Based on the results of FIGS. 4a-b, in one embodiment, the
thickness of the optical coupling layer 20 may be configured to be
in the range of approximately 500 .ANG. to 800 .ANG.. In another
embodiment, the thickness of the optical coupling layer 20 may be
adjusted according to various application scenarios.
[0048] FIG. 5 illustrates a relationship between light
transmittance of an exemplary OLED display panel and thickness of
an exemplary optical coupling layer consistent with disclosed
embodiments. As shown in FIG. 5, the abscissa represents the
thickness of the optical coupling layer 20 in a unit of nanometer
(nm), and the ordinate represents the light transmittance, T %, at
the light output side of the OLED display panel. Referring to FIG.
5, the light transmittance T %/o may be slightly declined as the
thickness of the optical coupling layer 20 gradually increases,
however, the light transmittance T % may be still within an
acceptable range of error. According to FIG. 5, when the thickness
of the optical coupling layer 20 is in the range of approximately
500 .ANG. to 800 .ANG., the OLED display panel may have a desired
light transmittance.
[0049] To further enhance the image performance of the OLED display
panel, in one embodiment, the light transmittance of the electrode
at the light output side in the OLED display panel may be
configured to be in the range of approximately 30% to 50%. The
total light transmittance of the light-output-side electrode
stacked with the optical coupling layer 20 may be equal to or
larger than approximately 65%.
[0050] FIGS. 6a-b illustrate a performance comparison of four
exemplary OLED display panels consistent with disclosed
embodiments. As shown in FIGS. 6a-b, L denotes an OLED display
panel including both the optical coupling layer 20 and the electron
transport layer 14 with a 1% volume of element Yb, M denotes an
OLED display panel including both the optical coupling layer 20 and
the electron transport layer 14 with a 3% volume of element Yb, N
denotes an OLED display panel including both the optical coupling
layer 20 and the electron transport layer 14 with a 5% volume of
element Yb, and P denotes an OLED display panel including both the
optical coupling layer 20 and the electron transport layer 14 with
a 10% volume of element Yb.
[0051] As shown in FIG. 6a, the abscissa represents the wavelength
of the light emitted from the OLED display panel in a unit of
nanometer (nm), and the ordinate represents the light
transmittance, T %, at the light output side of the OLED display
panel. The light transmittance may decrease to some extent as the
volume percentage of element Yb in the electron transport layer 14
increases.
[0052] As shown in FIG. 6b, the abscissa represents four exemplary
OLED display panels with different volume percentages of element Yb
in the electron transport layer 14, and the ordinate represents the
total sheet resistance of the light-output-side electrode combined
with the optical coupling layer 20, in a unit of ohms per square
(.OMEGA./square). As shown in FIG. 6b, the OLED display panel M,
with a 3% volume of element Yb in the electron transport layer 20,
may have the smallest sheet resistance as compared to the other
three OLED display panels L, N and P. That is, when the OLED
display panel M is provided with a 3% volume of element Yb in the
electron transport layer 20, the bias voltage applied to the OLED
display panel may be reduced. Meanwhile, the sheet resistance of
the disclosed OLED display panel M may be reduced by approximately
50% compared to the existing OLED display panels.
[0053] FIGS. 6a-b may further indicate that through disposing the
optical coupling layer 20 at the light output side of the OLED
display panel and introducing a volume percentage of element Yb
equal to or less than 3% into the electron transport layer 14, the
light transmittance of the OLED display panel may be effectively
improved, and the operation voltage may be reduced. Accordingly,
the performance of OLED display panel may be enhanced.
[0054] FIG. 7 illustrates a schematic structure diagram of another
exemplary OLED display panel consistent with the disclosed
embodiments. The similarities between FIG. 1 and FIG. 7 are not
repeated here, while certain differences may be explained.
[0055] As shown in FIG. 7, in the disclosed OLED display panel, the
second electrode may be the only light-output-side electrode, and
the light generated from the organic luminescent layer 13 may emit
from the stacked structure after successively passing through the
electron transporting layer 14 and the second electrode 12.
[0056] Referring to FIG. 7, in particular, the first electrode 11
may include a first transparent conductive film 111, a second
transparent conductive film 112, and a reflective film 113
sandwiched between the first transparent conductive film ill and
the second transparent conductive film 112. The second electrode 12
may include materials of silver or sliver-based alloy.
[0057] In practical applications, the respective layers of the
first electrode 11 may have various materials and thicknesses
according to various application scenarios, provided that the first
electrode has a desired hole injection capability and a desired
light reflectivity. For example, in one embodiment, the first
transparent conductive film 111 and the second transparent
conductive film 112 in the first electrode 11 may be composed of
indium tin oxide or indium zinc oxide, and the reflective film 113
may be composed of silver or silver-based alloy. The thickness of
the reflective film 113 may range from approximately 50 nm to 150
nm.
[0058] Similarly, the thickness of the second electrode 12 may also
vary according to various application scenarios, provide that the
second electrode 12 has a desired electron injection capability and
a desired light transmittance. For example, in one embodiment, the
second electrode 12 may be composed of silver-based alloy, wherein
the volume percentage of silver may be equal to or larger than
approximately 80%. The thickness of the second electrode 12 may
range from approximately 10 nm to 20 nm.
[0059] FIG. 8 illustrates a schematic structure diagram of another
exemplary OLED display panel consistent with the disclosed
embodiments. The similarities between FIG. 8 and FIG. 7 are not
repeated here, while certain differences may be explained.
[0060] As shown in FIG. 8, only the first electrode 11 may be
disposed at the light output side of the OLED display panel. That
is, the first electrode 11 may be the only light-output-side
electrode of the OLED display panel. The light generated by the
organic luminescent layer 13 may emit after passing through the
first electrode 11. In particular, the first electrode 11 may
comprise transparent conductive materials, and the materials of the
second electrode 12 may include silver or a silver-based alloy.
[0061] In practical design, the materials and thicknesses of the
first electrode 11 may vary according to various application
scenarios, provided that the first electrode has a desired hole
injection capability and a desired light transmittance. For
example, in one embodiment, the first electrode 11 may be composed
of indium tin oxide or indium zinc oxide. Similarly, the materials
and thicknesses of the second electrode 12 may also vary according
to various application scenarios, provided that the second
electrode 12 has a desired electron injection capability and a
desired reflectivity. For example, in one embodiment, the second
electrode 12 may be composed of a silver-based alloy, in which the
volume percentage of silver is equal to or larger than
approximately 80%, and the thickness of the second electrode may
vary between approximately 50 nm and 150 nm.
[0062] Furthermore, the organic luminescent layer 13 may include
organic luminescent materials for realizing white illumination. In
one embodiment, the organic luminescent layer 13 may include a red
light-emitting material, a green light-emitting material and a blue
light-emitting material. White light emission may be obtained by
mixing the lights emitted from the red, green and blue
light-emitting materials.
[0063] FIG. 9 illustrates a schematic diagram of another exemplary
OLED display panel consistent with disclosed embodiments. The
similarities between FIG. 1 and FIG. 9 are not repeated here, while
certain differences may be explained. As shown in FIG. 9, the OLED
display panel may further include a color filter layer 15 disposed
at the light output side of the OLED display panel, through which
the white light emitted by the OLED display panel may become
colored light.
[0064] When the organic luminescent layer 13 may include a red
light-emitting material, a green light-emitting material and a blue
light-emitting material, the red light-emitting material, the green
light-emitting material and the blue light-emitting material may
vary according to various application scenarios. For example, the
red and the green light-emitting materials may contain
phosphorescent materials. The blue light-emitting materials may
contain fluorescent materials, and the fluorescent materials may
include thermally activated delayed fluorescent materials. In
addition, the red, the green, and the blue light-emitting materials
may include host materials doped with guest materials. In
particular, the red light-emitting materials may comprise one host
material or two host materials, the green light-emitting materials
may comprise at least two host materials, and the blue-emitting
materials may comprise one host material or two host materials.
[0065] FIG. 10 illustrates a schematic diagram of another exemplary
OLED display panel consistent with disclosed embodiments. The
similarities between FIG. 1 and FIG. 10 are not repeated here,
while certain differences may be explained. As shown in FIG. 10,
the disclosed OLED display panel may further include a hole
transport layer 16 disposed between the first electrode 11 and the
organic luminescent layer 13.
[0066] All of the OLED display panels in the disclosed embodiments
may be fabricated in various approaches according to various
application scenarios. For example, in one embodiment, at the
beginning the first electrode 11 may be fabricated on the
substrate, then the respective layers between the first electrode
11 and the second electrode 12 may be sequentially formed, and
finally the second electrode 12 may be formed. In another
embodiment, the second electrode 12 may be first formed on the
substrate, then the respective layers between the first electrode
11 and the second electrode 12 may be sequentially formed, and
finally the first electrode 11 may be formed.
[0067] The present disclosure also provides an OLED display
apparatus. FIG. 11 illustrates a schematic diagram of an exemplary
OLED display apparatus 101 consistent with the disclosed
embodiments. Referring to FIG. 11, the OLED display apparatus 101
may comprise any one of the OLED display panels in disclosed
embodiments. For example, the disclosed OLED display apparatus 101
may be a mobile phone, a notebook computer, a smart wearable
device, and an information inquiry machine in public hall, etc.
Furthermore, the OLED display apparatus 101 may be any appropriate
type of content-presentation devices including any of the disclosed
OLED display panels. The disclosed OLED display apparatus 101 may
also exhibit the same advantages as the disclosed OLED display
panels.
[0068] Through introducing the element Yb with a volume percentage
equal to or less than 3% into the electron transport layer 14, the
disclosed OLED display panels and the OLED display apparatus may
solve the problems of the substantially high energy barrier at the
interface between the cathode and the electron transport layer 14
as well as the poor display performance. That is, the disclosed
OLED display panels and OLED display apparatus may be able to
reduce the substantially high energy barrier at the interface
between the cathode and the electron transport layer 14, improve
the electron injection capability and, accordingly, enhance the
display performance.
[0069] Moreover, through introducing the optical coupling layer 20
into the disclosed OLED display panels, the light transmittance of
the OLED display panels may be effectively improved and,
accordingly, the performance of the OLED display panels may be
further improved.
[0070] The description of the disclosed embodiments is provided to
illustrate the present invention to those skilled in the art.
Various modifications to these embodiments will be readily apparent
to those skilled in the art, and the generic principles defined
herein may be applied to other embodiments without departing from
the spirit or scope of the invention. Thus, the present invention
is not intended to be limited to the embodiments shown herein but
is to be accorded the widest scope consistent with the principles
and novel features disclosed herein.
* * * * *